1137 



what influence has tlie addition of a new substance A on the 

 temperature 7', and the pressure I\^ of the eutectical point under 

 its own vaj)Ourpressure with tlie phases B -\- C -{- L,, -|- G^. 



We may put tliis question also more generally ; for this we replace 

 the eutectical point witli the phases B -\- C -\- />„ -\- (r,, by a qua- 

 druplepoint with the phases F -\- F' -\- L,,-\-G,,; F and F' are 

 then either the components B and (' or binary compounds of 

 i5 and 6'. 



When we take a constant pressure so high, that the vapour 

 disappears, and when we add the substance A to tlie equilibrium 

 F -\- F' -\- Lg then the tempeiature is lowered. We may express 

 this also in the following way : the common meltingpoint or point 

 of inversion of two sul^stances is lowered under a constant pressure 

 by addition of a third substance '). 



We now must put the question : what influence has the addition 

 of a new substance A on the temperature 7', and on the pressure 

 Pa of the quadruplepoint with the phases F-\-F' -f- L^ -\- G^- 



Firstly we shall consider the general case treated in communication 

 VIII more in detail. Instead of the equations (2), (3), and (4) (VIII) 

 we write : 



[(,7; a)r H- {y -/i)s] dx + \{x ~ a)s + {il-^)t] dy=AdP—BdT . (I) 



L(.f,-«>- + {y.-m<^'>= + [(."x-«)'^ + {y.-mdy =- {A \ C) dP- {B^D)dT (2) 



!(«'-«);■ + (/3'-,i).sJ,/.^• 4- [(«'-«).^ -h {[i'-mdy = (A-A) dP- {B-B')dT . (3) 



We find from (1) and (3), eliminating dy. 

 E{rt-syw = [\{a'-.v)A + i.v-a)A'\ s + \{^'-y)A + {y-i3)A'\t] dP 

 - [|(«'-.f)Z?+ {.V - a)B'\s + m'-y)B + {y ^)B'\t] d.T 

 We find from (2) and (3): 



F, {rt—s') dx — j 



[|(«'-.i^)yl4-(.^^-«)^4^f («'-«)Cl. + {G^'-^'J.4 + (2/-/^K-, {ii'-'^)C\qdP (5) 

 -[\{a'-x,)B y {.,,-a)B' ^-{<^'-^)D\s-^W-!J,)B+{y-^)B -^{^'-^)D\qdT ] 



Herein E is equal to : 



={i3'-^){x-a)^-{a'-a){^'- y). 



We find E^ by substituting in A\i'i and //i for ,i' and //. For the sake 

 of abbreviation we put the following: 



1) F. A. H. ScHREiNEMAKERS. Heterog. Gleichgewichte 111'. 



74* 



(4) 



